The catalytic hydrogenation of carbonyl-containing compounds, e.g., esters, to produce their corresponding alcohols, is potentially of great commercial value. Catalysts traditionally employed for such conversions include copper chromite based materials, frequently containing a promoter such as barium. Unfortunately, these catalysts typically require high pressure to achieve commercially attractive reaction rates for the hydrogenation of esters, i.e., pressures in excess of 3000 psig. In addition, chromium and barium present toxicity and environmental concerns which must be dealt with if one is to economically and safely use these materials on a commercial scale.
More recently, substantial amounts of research have been carried out in efforts to develop hydrogenation catalysts capable of reducing carbonyl-containing compounds, e.g., organic acids and esters, to alcohols at reduced pressures. While such catalysts are capable of promoting the hydrogenation of carbonyl-containing compounds to produce alcohols, one problem with such materials is the need to run at very low liquid hourly space velocities in order to achieve suitably high conversion levels.
Another problem frequently encountered with such prior art low pressure catalyst systems when employed for the reduction of carbonyl-containing compounds such as aldehydes and ketones, is their lack of selectivity to the desired alcohol product, such catalysts frequently being too active and thus producing product which results from reaction of substrate with additional hydrogen.
Yet another problem encountered with such prior art low pressure catalyst systems, such as Raney nickel, is the ease of handling of such catalysts, which are frequently pyrophoric, and thus require special handling to avoid fire hazard.